Field of the Invention
The present invention relates to mobile communication.
Related Art
3GPP (3rd Generation Partnership Project) LTE (Long Term Evolution) that is an advancement of UMTS (Universal Mobile Telecommunication System) is being introduced with 3GPP release 8. In 3GPP LTE, OFDMA (orthogonal frequency division multiple access) is used for downlink, and SC-FDMA (single carrier-frequency division multiple access) is used for uplink. The 3GPP LTE adopts MIMO (multiple input multiple output) having maximum four antennas. Recently, a discussion of 3GPP LTE-A (LTE-Advanced) which is the evolution of the 3GPP LTE is in progress.
As set forth in 3GPP TS 36.211 V10.4.0, the physical channels in 3GPP LTE may be classified into data channels such as PDSCH (physical downlink shared channel) and PUSCH (physical uplink shared channel) and control channels such as PDCCH (physical downlink control channel), PCFICH (physical control format indicator channel), PHICH (physical hybrid-ARQ indicator channel) and PUCCH (physical uplink control channel).
Meanwhile, in a next-generation mobile communication system, it is expected that a small cell of which a cell coverage radius is small is added in coverage of a macro cell and that the small cell handles a more amount of traffic. However, although it is preferable that a user equipment (UE) does not perform association, i.e., selection or reselection, on the small cell with having high cell loading due to such excessive traffic, there is no conventional method in which the UE can distinguish the small cell having the high cell loading from other small cells.